CN117136096A

CN117136096A - Printing structure for supporting electrospun fibers for filtration

Info

Publication number: CN117136096A
Application number: CN202180084088.8A
Authority: CN
Inventors: P·A·伊格纳西奥-德莱昂; D·A·桑斯特; K·T·威利斯; J·R·穆迪; M·P·格尔兹; M·A·约德; D·D·劳尔; D·B·莫拉维茨; A·苏塔尔
Original assignee: Donaldson Co Inc
Current assignee: Donaldson Co Inc
Priority date: 2020-12-17
Filing date: 2021-11-22
Publication date: 2023-11-28
Also published as: KR20230122038A; WO2022132397A1; JP2023554604A; EP4263221A1

Abstract

Embodiments herein relate to a method for manufacturing a filter medium including printing a first three-dimensional structure using an additive manufacturing process and depositing a first fine fiber layer on the first three-dimensional structure using an electrospinning process to form a first medium assembly. Other embodiments are also contemplated herein.

Description

Printing structure for supporting electrospun fibers for filtration

The present application is filed as PCT international patent application at month 11 22 of 2021 in the name of tansen company (Donaldson Company, inc.) (a company of american countries, all the applicant of the designated countries) and U.S. citizen Patricia a. Ignacio-de Leon, U.S. citizen durin a. Zastera, U.S. citizen klentt. Willis, U.S. citizen Jared r.moudy, U.S. citizen Matthew p. Goertz, U.S. citizen Mikayla a. Yoder, U.S. citizen David d.lauer, U.S. citizen Davis b.moravec, and U.S. citizen Suthar (the inventor of the designated countries), and claims priority of U.S. provisional patent application No. 63/127,079 filed at month 12 of 2020, the contents of which are incorporated herein by reference in their entirety.

Technical Field

Embodiments herein relate to using printed structures made by additive manufacturing methods as supports for and in combination with electrospun fibers to create composite structures for filter media.

Background

Fine fibers are often used in filter media applications. These fibers are applied to substrates and used in liquid and air filtration applications.

Drawings

The aspects may be more completely understood in consideration of the following drawings (figures), in which:

FIG. 1 is a cross-sectional view of a fin assembly for a media assembly, which is an example of a three-dimensional printed structure formed by additive manufacturing, according to various embodiments herein.

FIG. 2 is a top view of the fin assembly of FIG. 1 according to various embodiments herein.

Fig. 3 is a cross-sectional view of a first three-dimensional printed structure including pillars on top of the fin assembly of fig. 1, according to various embodiments herein.

Fig. 4 is a top view of the first three-dimensional printed structure of fig. 3, according to various embodiments herein.

Fig. 5 is a cross-sectional view of a first three-dimensional printed structure including pillars on top of the fin assembly of fig. 1 and also having surface roughness features shown in close-up view on a top surface of at least one pillar, according to various embodiments herein.

FIG. 6 is a cross-sectional view of a first media assembly including the first three-dimensional structure of FIG. 3 and a first fine fiber layer vacated above a fin assembly, according to various embodiments herein.

FIG. 7 is a cross-sectional view of an alternative first media assembly including the first three-dimensional structure of FIG. 3 and a first fine fiber layer in contact with a fin assembly, according to various embodiments herein.

FIG. 8 is a cross-sectional view of a second media assembly including a second column layer and a second fine fiber layer vacated above the first fine fiber layer, according to various embodiments herein.

FIG. 9 is a cross-sectional view of an alternative fin assembly having a gradient spacing of a first fin layer, which is an example of a three-dimensional printed structure formed by additive manufacturing, according to various embodiments herein.

FIG. 10 is a top view of the gradient fin assembly of FIG. 9, wherein both the first fin layer and the second fin layer may be observed to have a gradient spacing, according to various embodiments herein.

FIG. 11 is a cross-sectional view of yet another alternative fin assembly having a first pillar layer with a height gradient of pillars, according to various embodiments herein.

While the embodiments are susceptible to various modifications and alternative forms, details thereof have been shown by way of example and the accompanying drawings and will be described in detail. However, it should be understood that the scope of this document is not limited to the particular aspects described. On the contrary, the intention is to cover modifications, equivalents, and alternatives falling within the spirit and scope of the application.

Detailed Description

Additive manufacturing techniques (also known as 3D printing) allow for very accurate manufacturing of objects using digital models. The material layer is deposited in precise locations to form the desired object. 3D printing allows more flexibility with respect to the size and shape of the object than injection molding and other manufacturing techniques, as there is no limit to the shape that can be removed from the mold. Another advantage of 3D printing is that highly permeable structures can be formed using 3D printing.

Structures formed using 3D printing may be used in filter media comprising fine fibers to increase the usable surface area of the fine fibers, i.e., the surface area of the fine fibers that is not in direct contact with an underlying substrate, without increasing the fine fiber basis weight. Fine fibers (such as nanofibers) conform to typical substrates used in filter media. The three-dimensional structure may be constructed using 3D printing and other manufacturing techniques and used in combination with the fine fiber layer to create the following filter media: the available surface area per unit of fine fiber per base area is increased without increasing the thickness of the fine fiber layer. As a result, the face velocity through the fine fiber layer is reduced, thereby reducing the pressure drop. The three-dimensional structure also provides additional surface area for dust loading (dustloading) and increased dust holding capacity.

The three-dimensional structure may be covered with a fine fiber layer to form a first media component. Alternatively, an additional second three-dimensional structure may be printed on top of the first media component, and then a second fine fiber layer may be formed on top thereof to form the media component. Multiple additional layers are also possible, wherein the additional layers may include both three-dimensional structural components and additional fine fiber layers.

A media assembly comprising a 3D printed structure and a fine fiber layer may be used as a filter media without any other substrate. Alternatively, a media component comprising a 3D printed structure and a fine fiber layer may be formed or positioned on a substrate. The media assemblies described herein may be further assembled with other conventional filter structures to make filter composite layers or filter units. Examples of substrates may be nonwoven, woven, film, cellulosic media, glass media, synthetic media, scrims, or expanded metal supports. The media assemblies described herein may be used in combination with many other types of media, such as conventional media, to improve filter performance or life.

The perforated structure may be used to support the media assembly under the influence of fluid under pressure through the media. The filter structures described herein may also be combined with additional layers of perforated structure, scrims (such as high permeability, mechanically stable scrims), and additional filtration layers (such as separate loading layers). In one embodiment, such multi-zone media combination is housed in a filter cartridge typically used to filter non-aqueous liquids.

The media components, with or without a substrate, may be rolled, pleated, stacked into layers, or otherwise assembled to form a filter element. The 3D structure may provide embossed features, such as pleat spacing features.

Filter elements formed using the 3D structures described herein may have a variety of flow path configurations. In one example, the dirty fluid passes through the filter media having a pleated configuration, a stacked configuration, or both. In another example, dirty fluid enters an open groove on the dirty air side of a filter assembly (filter pack). Because the grooves are sealed on opposite ends, air is forced through the filter media into adjacent grooves. The filtered air exits the filter assembly through grooves that open on the clean air side of the filter element. In some examples, the filter element is cylindrical, dirty fluid enters the core of the element, passes through the filter media, and exits as cleaner filtered fluid at the exterior of the filter element.

In another example, a "flow by" flow path is used. By filtering is meant that the fluid never passes through the filter media. There are channels formed by the filter media and through which fluid flows. Turbulence in the flow causes particles to contact and become trapped in the filter media. This type of configuration has pressure drop advantages, typically at the cost of lower fractionation efficiency. Filter elements having such a configuration may be used with the media assemblies described herein. Filter elements having a flow-through configuration are further described in the following commonly owned patent publications incorporated herein by reference in their entirety: WO 2019032773 entitled flid FILTRATION APPARATUSES, SYSTEMS, AND METHODS [ FLUID FILTRATION devices, systems and METHODS ].

If a stacked configuration of media assembly sheets is used, the stack of media assemblies may change configuration in one or more dimensions. The individual sheets in the stack may also differ from each other. For example, discrete 3D features may appear on a first sheet and not on other sheets.

Each substrate or substrate sheet may comprise a grid of 3D structures. In some examples, the 3D structures within the grid may have different heights that move in a direction across the substrate.

Filter assemblies with fine fiber layers can have significant pressure drops. The addition of the 3D structures described herein may reduce the pressure drop of a filter assembly having a fine fiber layer. In some prior art systems where the fine fiber layer does not have high adhesion strength, the fine fiber layer may also fall off the substrate. Adding 3D structures may reduce the likelihood of sloughing.

Examples of 3D structures that may be used for the filter assembly will now be described with reference to fig. 1 to 5.

3D Structure (FIGS. 1-5)

The terms "3D structure" and "three-dimensional structure" are used interchangeably herein.

Referring now to fig. 1-5, examples of three-dimensional printed structures that may be incorporated into filter media with fine fiber layers will be discussed. These structures are merely examples, and many options exist for the 3D structures described herein. Fig. 1 and 2 illustrate a three-dimensional printed structure 100 formed from a first fin layer 104 and a second fin layer 106. The three-dimensional printed structure 100 may also be referred to as a fin assembly. The fin assembly may be formed by additive manufacturing, injection molding, or by other manufacturing techniques.

In some embodiments, the 3D structure (as the term is used herein) has a dimension, such as a height, width, or length dimension, of greater than or equal to 1, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 microns. In some embodiments, the dimensions may be less than or equal to 2000, 1900, 1800, 1700, 1600, 1500, 1400, 1300, 1200, 1100, or 1000 microns. In some embodiments, the dimensions may fall within a range of 1 to 2000 microns, or 100 to 1900 microns, or 200 to 1800 microns, or 300 to 1700 microns, or 400 to 1600 microns, or 500 to 1500 microns, or 600 to 1400 microns, or 700 to 1300 microns, or 800 to 1200 microns, or 900 to 1100 microns, or may be about 1000 microns.

The first fin layer includes a plurality of first fins 104 oriented parallel to one another. In the view of fig. 1, the first fin extends away from the viewer. The second fin layer includes a plurality of second fins oriented parallel to each other and perpendicular to the first fins. The second fins are stacked on the first fins. The fins in the examples of the drawings are each generally rectangular parallelepiped.

The fin assembly may be used as a 3D structure as described herein and incorporated into a media assembly. Alternatively, other structures may be added to the fin assembly, such as the columns shown in fig. 3-4.

Fig. 3 is a cross-sectional view of another three-dimensional printed structure 100 including pillars 110 on top of the fin assembly of fig. 1. Fig. 4 is a top view of the first three-dimensional printed structure of fig. 3. The pillars may be formed by 3D printing or by other manufacturing methods. At least some of the pillars are formed at an intersection location where the first fin and the second fin intersect. In some embodiments, all of the pillars are formed at an intersection location where the first fin and the second fin intersect.

The columns, the fins comprising the fin assembly, and the spacing of the columns and fins can be of various sizes. In some embodiments, the dimensions of the spacing between pillars, the spacing between fins, fin width, fin length, and fin height are greater than or equal to 1, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 microns. In some embodiments, the dimensions may be less than or equal to 2000, 1900, 1800, 1700, 1600, 1500, 1400, 1300, 1200, 1100, or 1000 microns. In some embodiments, the dimensions may fall within a range of 1 to 2000 microns, or 100 to 1900 microns, or 200 to 1800 microns, or 300 to 1700 microns, or 400 to 1600 microns, or 500 to 1500 microns, or 600 to 1400 microns, or 700 to 1300 microns, or 800 to 1200 microns, or 900 to 1100 microns, or may be about 1000 microns.

Fig. 5 is a cross-sectional view of a first three-dimensional printed structure 100 including pillars 110 on top of the fin assembly of fig. 1. According to various embodiments herein, the 3D printed structure of fig. 5 also has surface roughness features 500, shown in close-up view, on the top surface of at least one pillar. The surface roughness may be provided at all or only some of the top surfaces of the pillars. The surface roughness may be provided at other areas of the 3D structure including, but not limited to, some or all of the side surfaces of the pillars, some or all of the top surfaces of the fins, some or all of the side surfaces of the fins, some or all of the bottom surfaces of the fins.

Additional structures may be deposited on the top surface of the pillars using 3D printing techniques to create surface roughness. Alternatively, particles or fibers may be incorporated into the surface layer of the 3D printed material to create the surface roughness features. In some embodiments, the size of such surface roughness features may be greater than or equal to 10, 100, 200, 300, 400, or 500 nanometers. In some embodiments, the dimensions may be less than or equal to 1000, 900, 800, 700, 600, or 500 nanometers. In some embodiments, the dimensions may fall within a range of 10 to 1000 nanometers, or 100 to 900 nanometers, or 200 to 800 nanometers, or 300 to 700 nanometers, or 400 to 600 nanometers, or may be about 500 nanometers.

Medium component examples and methods of formation (FIGS. 6-8)

Fig. 6 is a cross-sectional view of a first media assembly 600 including the first three-dimensional structure 100 of fig. 3 and a first fine fiber layer 604 vacated above the fin assembly, in accordance with various embodiments herein. A first fine fiber layer is deposited after the pillars 110 are formed on the first media pack 600. At least some of the filaments of the first layer of filaments are in contact with the top surface of the pillars 110, wherein the top surface of the pillars is the surface furthest from the second fins 106. There are gaps 610 between the first fine fiber layer 604 and the first surface of the second fin 106. The height of the gaps 610 between the pillars (which may also be described as the sagging amount of the emptied fine fiber layer) will depend on the pitch of the pillars.

Deposition of fine fiber layer 604 may occur after 3D structure 100 has been constructed. The deposition of fine fiber layer 604 may be one of the last steps that occurs in addition to the post-treatment step.

Close-up view 606 shows that the fine fiber layer is not a unitary structure. Alternatively, the fine fiber layer is comprised of discrete fibers that intersect in the fine fiber layer and define open spaces.

FIG. 7 is a cross-sectional view of an alternative first media assembly 700 that includes the first three-dimensional structure and fine fiber layer 704 of FIG. 3. In contrast to the emptied fine fiber layer 604 of fig. 6, the fine fiber layer 704 has many fibers in contact with the fin assembly and is present in the spaces between the columns 110. The pillars 110 minimize potential dust packing in the fine fiber layer 704, allowing for slower differential pressure build up and thus longer filter life. The fine fiber layer 704 is deposited after the pillars 110 are formed on the fin assembly. The fine fiber layer 704 may be referred to as a conforming fine fiber layer.

The emptied fine fiber layer of fig. 6 improves the ability of the pulse cleaning filter media to remove dust compared to the fine fiber layer 704 contacting the fin assembly.

Fig. 8 is a cross-sectional view of a second media assembly 800 including a second column layer and a second fine fiber layer emptied above the first fine fiber layer, in accordance with various embodiments herein. The second media pack 800 includes all of the components of the first media pack 600 of fig. 6, including the fin assembly, the first column layer 110, and the vacated first fine fiber layer 604 defining the gap 610. The second media pack 800 further includes a second pillar layer 808 formed on the top surface of the first pillar 110. The first fine fiber layer 604 is also on top of the first column. Despite the first fine fiber layer 604 in between, the second column layer may still be formed because of the precise control of the 3D printing technique and because the material forming the second column layer 708 is a thermoplastic material that flows through the pores of the fine fiber layer. The material flows around and through any individual intermediate fibers of the fine fiber layer and is deposited on the top surface of the first pillar.

The second media pack 800 also includes a vacated second fine fiber layer 814. A second fine fiber layer is deposited after the pillars 808 are formed on the first pillars 110. At least some of the filaments of the second layer of filaments are in contact with the top surface of the second pillars 808, where the top surface of the pillars is the surface furthest from the second fins 106 and the rest of the 3D structure. A gap 818 exists between the second fine fiber layer 814 and the first fine fiber layer 614. The height of the gaps 818 between the columns (which may also be described as the sagging amount of the emptied fine fiber layer) will depend on the spacing of the columns.

The media assembly of fig. 8 will have a lower differential pressure than a media assembly comprising two stacked fine fiber layers on a conventional substrate without a 3D structure. In various embodiments, the first fine fiber layer is different from the second fine fiber layer. For example, the first fine fiber layer may have a first pore size and the second fine fiber layer has a second, larger pore size. In another example, a second fine fiber layer upstream of the first fine fiber layer is configured to better repel any wetting fluid and the first fine fiber layer is configured to optimize particulate filtration.

Although fig. 8 shows two fine fiber layers interspersed with two pillar layers, third, fourth, and fifth fine fiber layers and pillar layers interspersed with each other may also be included.

In the case where a first media pack comprising 3D structures (as shown in the various examples of the drawings) is used on top of the filter substrate, the presence of the first media pack 600 reduces the masking effect of the fine fiber layer on the underlying substrate.

In various embodiments, the media component provides a direct, non-tortuous, open path for the fluid to be filtered to a particular point in the depth of the thickness of the media component. Such a path may extend from a first side to a second side of the 3D printed structure. Such a path resembles a vent tube structure that provides a fluid passageway to a particular desired location. Such a construction helps to fully utilize the media pack through its thickness. This structure creates a passageway for fluid to enter the interior of the filter media at a specific location and at a predetermined depth. Such structures may help increase contaminant capacity and/or flux.

The 3D structures described herein may also be used as scaffolds for cell growth, such as in the food and beverage industry, pharmaceutical industry or biological industry.

The media assemblies described herein can provide a vacation structure for the top layer of the loading layer of the membrane, thereby providing a low solidity, high volume structure for extended life.

Gradient structure

The precise control provided by the additive manufacturing method and the ability to vary the material added to the structure at each location enables 3D structures to have size gradients, such as height gradients of repeating structures, width gradients of repeating structures, thickness gradients of repeating structures, pitch gradients of repeating structures, and shape gradients of repeating structures. Gradients in the physical structures can in turn lead to gradients in the fine fiber coverage of fibers deposited on these structures. Gradients of material composition may also be formed in any dimension of the structure.

Specific choices of variable spacing and gradient dimensions can be based on flow modeling to optimize pressure drop and loading.

Gradient Structure examples (FIGS. 9 to 11)

Fig. 9 is a cross-sectional view of an alternative fin assembly 900, which may also be referred to as a 3D structure 900, having a gradient spacing of first fins 904 within a first fin layer. Moving from the left side of the fin assembly to the right side of the fin assembly in the view of fig. 9, the fins 904 are positioned progressively farther apart. FIG. 10 is a top view of the gradient fin assembly of FIG. 9, wherein both the first fin layer and the second fin layer may be observed to have a gradient spacing, according to various embodiments herein. Moving from a first side of the fin assembly to a second side of the fin assembly in fig. 10 (which is from top to bottom in the view of fig. 10), the fins 906 of the second fin layer are positioned progressively farther apart.

Another example of a gradient structure is shown in fig. 11, which is a cross-sectional view of yet another alternative fin assembly 1100 or 3D structure. The first pillar layer 1110 includes pillars having a height gradient of the pillars. The first pillars have a first height, the second pillars have a second height that is less than the first height, and the third pillars have a third height that is less than the second height. In some embodiments, the amount of difference between the first height, the second height, and the third height may be greater than or equal to 1, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000 microns. In some embodiments, the difference may be less than or equal to 2000, 1900, 1800, 1700, 1600, 1500, 1400, 1300, 1200, 1100, or 1000 microns. In some embodiments, the difference may fall within a range of 1 to 2000 microns, or 100 to 1900 microns, or 200 to 1800 microns, or 300 to 1700 microns, or 400 to 1600 microns, or 500 to 1500 microns, or 600 to 1400 microns, or 700 to 1300 microns, or 800 to 1200 microns, or 900 to 1100 microns, or may be about 1000 microns.

Method of forming a media assembly

Many different methods are contemplated herein, including but not limited to methods of making media packs, methods of using media packs, and the like. Aspects of the system/device operations described elsewhere herein may be performed as operations according to one or more methods of various embodiments herein.

In an embodiment, a method for manufacturing a filter medium includes printing a first three-dimensional structure using an additive manufacturing process and depositing a first fine fiber layer on the three-dimensional structure using an electrospinning process to form a first medium assembly.

In an embodiment, the method may further include printing a second three-dimensional structure on the first media component using an additive manufacturing process to form a second media component.

In an embodiment, the method may further include depositing a second fine fiber layer on the first media component after printing the second three-dimensional structure to form a second media component.

In an embodiment, the first three-dimensional structure is printed on the substrate.

In an embodiment of the method, the substrate is rolled up to form a filter unit.

In an embodiment, the method may further include forming a plurality of sheets of the first media assembly and stacking the plurality of sheets to form the filter unit.

In an embodiment of the method, each sheet comprises a plurality of first media subassemblies.

In an embodiment of the method, the first three-dimensional structure comprises a plurality of first fins oriented parallel to each other and a plurality of second fins oriented parallel to each other and perpendicular to the first fins, wherein the second fins are stacked on the first fins.

In an embodiment of the method, the first three-dimensional structure further comprises a plurality of pillars formed on the first surface of the second fin.

In an embodiment of the method, at least some of the pillars are formed at an intersection location where the first fin and the second fin intersect.

In an embodiment of the method, when the first fine fiber layer is deposited after the pillars are formed on the first three-dimensional structure, a media assembly is formed that includes the emptied first fine fiber layer, at least some of the fine fibers of the first fine fiber layer are in contact with a top surface of the pillars that is furthest from the second fins, and a gap exists between the first fine fiber layer and the first surface of the second fins.

In an embodiment of a method for forming a media component comprising a conformable first fine fiber layer, the first fine fiber layer is deposited after forming pillars on a first three-dimensional structure, then the fine fiber layer is located between the pillars, and at least some of the fine fibers are in contact with a first surface of a second fin.

In an embodiment, a method for manufacturing a filter medium is included that includes the step of printing a first three-dimensional structure using an additive manufacturing process. The method comprises the following substeps: printing a plurality of first fins oriented parallel to each other; printing a plurality of second fins oriented parallel to each other and perpendicular to the first fins, wherein the second fins are stacked on the first fins; and printing a first plurality of pillars forming a first pillar layer formed on the first surface of the second fin. The method further includes depositing a first fine fiber layer on the three-dimensional structure using an electrospinning process to form a first media assembly.

In an embodiment, the method may further include printing a second three-dimensional structure on the first media component using an additive manufacturing process to form a second media component, wherein the second three-dimensional structure includes a second plurality of pillars forming a second pillar layer, wherein each of the pillars of the second plurality of pillars is formed atop one of the pillars of the first plurality of pillars, thereby forming a second media sub-component.

In an embodiment, the method may further include, after printing the second post layer, depositing a second fine fiber layer on the second media subassembly using an electrospinning process to form the first media subassembly.

In an embodiment, the material of the 3D printed structure comprises nanoparticles, fibers, nanofibers, additives or chemical treatments.

In an embodiment, the method includes altering surface roughness, altering fine fiber adhesion, and reducing dust adhesion as compared to a material without a chemical treatment or added particles.

In an embodiment of the method, the first three-dimensional structure defines a direct, non-tortuous, open channel from a first side to a second side of the three-dimensional structure.

Material for 3D structures

Various materials are suitable for creating the 3D structures described herein. Such materials include, but are not limited to, thermoplastic polymers including, but not limited to, polyamides, polypropylenes, polyurethanes, polyethylenes, polylactic acids, acrylonitrile butadiene styrene, and copolymers, mixtures, or derivatives thereof.

The materials used for 3D printing are selected to be compatible with the end application of the particular filter element. The materials used for 3D printing are selected to be chemically compatible and to have suitable physical properties to interact with the electrospun fibers and the conditions of the electrospinning process.

3D printing process

The 3D structures described herein may be formed using an additive manufacturing process, referred to herein as three-dimensional (3D) printing. The 3D structures produced using 3D printing may include unique and fine structural details, including those with high aspect ratios. The fine features incorporated into the 3D structures described herein may include, but are not limited to, pillars, fins, intersecting fins, differently distributed honeycomb cell structures with different pore sizes, uniformly distributed honeycomb cell structures with uniform pore sizes, fine struts, fine mesh structures, gradient cell structures throughout the material, threads, ridges, micro-surfaces imparting roughness and additional surface area, open cavities, central apertures, and the like. In various embodiments, the 3D structure may be 3D printed or include highly porous portions. In other embodiments, the 3D printing process may mix various materials to create a 3D structure.

Porosity of printing material

The printing material of the structures described herein may be porous to allow fluid to flow through the structure. Such porosity may be achieved during the printing process by defining many and frequent open spaces that interpenetrate the solid material portions. Examples of structures defining a number of open areas include the fin assemblies shown herein. These open areas allow fluid to flow through the structure.

In some embodiments, the open area of the end cap or pleat guide structure may be greater than or equal to 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, or 70%. In some embodiments, the open area may be less than or equal to 85%, 83%, 81%, 79%, 78%, 76%, 74%, 72%, or 70%. In some embodiments, the open area may fall within a range of 50% to 85%, or 52% to 83%, or 55% to 81%, or 58% to 79%, or 60% to 78%, or 62% to 76%, or 65% to 74%, or 68% to 72%, or may be about 70%.

Another way in which porosity can also be achieved is to select a material for the structure that is itself porous or that can be modified to be porous after printing. Some 3D printed materials contain particles of thermoplastic material of a different type than the rest of the material, such as spheres. These particles may partially solidify after printing and dissolve out of the structure. Another option is to selectively bake or etch away particles included in the material of the structure. These processes create void spaces within the printed material, thereby increasing the porosity of the material.

For the purposes of this disclosure, the term "aperture size" refers to the space formed by the material within the printed structure. The pore size of the media may be estimated by looking at an electronic photograph of the media. The average pore size of the media can also be calculated using a capillary flow porosimeter available from Porous Materials Inc. of Issat, N.Y. having model APP 1200 AEXSC.

In the context of a filter assembly for gas separation, in some embodiments, the average pore size of the printed material may be greater than or equal to 0.3 nanometers, 0.6 nanometers, 0.9 nanometers, 1.2 nanometers, or 1.5 nanometers. In some embodiments, the average pore size may be less than or equal to 3.0 nanometers, 2.6 nanometers, 2.2 nanometers, 1.9 nanometers, or 1.5 nanometers. In some embodiments, the average pore size may fall within a range of 0.3 nanometers to 3.0 nanometers, or 0.6 nanometers to 2.6 nanometers, or 0.9 nanometers to 2.2 nanometers, or 1.2 nanometers to 1.9 nanometers, or may be about 1.5 nanometers.

In other filtration settings (such as ePTFE) where maintaining the permeability of existing media is a priority, in some embodiments the average pore size may be greater than or equal to 0.1 microns, 0.2 microns, 0.4 microns, 0.5 microns, 0.7 microns, 0.8 microns, 0.9 microns, 1.1 microns, 1.2 microns, 1.4 microns, or 1.5 microns. In some embodiments, the average pore size may be less than or equal to 3.0 microns, 2.8 microns, 2.7 microns, 2.6 microns, 2.4 microns, 2.2 microns, 2.1 microns, 2.0 microns, 1.8 microns, 1.6 microns, or 1.5 microns. In some embodiments, the average pore size may fall within a range of 0.1 to 3.0 microns, or 0.2 to 2.8 microns, or 0.4 to 2.7 microns, or 0.5 to 2.6 microns, or 0.7 to 2.4 microns, or 0.8 to 2.2 microns, or 0.9 to 2.1 microns, or 1.1 to 2.0 microns, or 1.2 to 1.8 microns, or 1.4 to 1.6 microns, or may be about 1.5 microns.

In other filtration contexts (such as the semiconductor arts) where maintaining the permeability of existing media is a priority, in some embodiments the average pore size may be greater than or equal to 0.01 microns, 0.02 microns, 0.03 microns, 0.04 microns, or 0.05 microns, or may be an amount falling within a range between any of the foregoing.

In the context of filter assemblies using nonwoven composite materials, in some embodiments, the average pore size of the printed material may be greater than or equal to 15 microns, 17 microns, 18 microns, or 20 microns. In some embodiments, the average pore size may be less than or equal to 25 microns, 23 microns, 22 microns, or 20 microns. In some embodiments, the average pore size may fall within a range of 15 microns to 25 microns, or 17 microns to 23 microns, or 18 microns to 22 microns, or may be about 20 microns.

In the context of filter media where minimizing pressure drop is important, the average pore size of the printed material may be greater than or equal to 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1.0mm in some embodiments. In some embodiments, the average pore size may be less than or equal to 2.0mm, 1.8mm, 1.6mm, 1.4mm, 1.2mm, or 1.0mm. In some embodiments, the average pore size may fall within a range of 0.5mm to 2.0mm, or 0.6mm to 1.8mm, or 0.7mm to 1.6mm, or 0.8mm to 1.4mm, or 0.9mm to 1.2mm, or may be about 1.0mm.

Incorporation of chemicals, additives or particles

Particles or additives may be added to the 3D structure for a variety of purposes, including to help guide the fine fibers to a desired location, to increase the adhesion of the fibers to the 3D structure, and to increase the adhesion of the 3D structure to the substrate.

Chemical treatments may be added during or after the manufacturing process to provide additional benefits including changing the contact angle of the material surface, modifying the surface roughness, increasing fine fiber adhesion, and reducing dust adhesion.

Examples of additives that may be added to the 3D structure include hydrophobic additives, and adhesion-increasing additives (e.g., pressure sensitive adhesives). Examples of particles that may be added to the 3D structure include adsorbents such as activated carbon, silica gel, metal Organic Frameworks (MOFs), and molecular sieves. In addition, a catalyst such as MnO or Pt may be included in the 3D structure.

Electrospinning method and fine fiber example

Options for the method of depositing the fine fiber layer, as well as examples of fine fiber materials and components, are described in the following three patent publications, which are commonly owned with the present application and are incorporated herein by reference in their entirety: WO 2013/044014A1 (in particular page 30, example 1), WO 2017/177033 A1 (in particular page 31, method of preparation, example 1) and WO 2013/043987 (in particular page 23, reference example 4). Nanofibers are examples of fine fibers that may be used with the assemblies described herein. Other examples of fine fibers may include meltblown fibers, spunbond fibers, meltblown fibers, and melt electrospun fibers.

It should be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a composition containing "a compound" includes a mixture of two or more compounds. It should also be noted that the term "or" is generally employed in its sense including "and/or" unless the context clearly dictates otherwise.

It should also be noted that, as used in this specification and the appended claims, the phrase "configured to" describes a system, apparatus, or other structure constructed or arranged to perform a particular task or to employ a particular configuration. The phrase "configured to" may be used interchangeably with other similar phrases such as being arranged and configured, constructed and arranged, constructed, manufactured and arranged, etc.

All publications and patent applications in this specification are indicative of the level of skill of those skilled in the art to which this application pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

As used herein, reference to a range of numerical values by endpoints is intended to include all numbers subsumed within that range (e.g., 2 to 8 includes 2.1, 2.8, 5.3, 7, etc.).

The title as used herein is provided for consistency with recommendations at 37cfr 1.77, or otherwise providing organizational cues. These headings should not be construed as limiting or characterizing the application(s) set forth in any claims that may be issued by the present disclosure. By way of example, although the headings refer to "technical field," such claims should not be limited by the language chosen under this heading to describe the so-called technical field. Furthermore, the description of a technology in the "background" does not constitute an admission that the technology is prior art to any application(s) in this disclosure. Neither should the "summary be considered as characterizing the application(s) set forth in the appended claims.

The embodiments described herein are not intended to be exhaustive or to limit the application to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may understand and appreciate the principles and practices. As such, aspects have been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope herein.

Claims

1. A method for manufacturing a filter media, comprising:

a. printing a first three-dimensional structure using an additive manufacturing process; and

b. a first fine fiber layer is deposited on the first three-dimensional structure using an electrospinning process to form a first media assembly.

2. The method of claim 1, further comprising printing a second three-dimensional structure on the first media component using the additive manufacturing process to form a second media component.

3. The method of claim 2, further comprising depositing a second fine fiber layer on the first media component after printing the second three-dimensional structure to form a second media component.

4. A method according to any one of claims 1 to 3, wherein the first three-dimensional structure is printed on a substrate.

5. The method of claim 4, wherein the substrate is rolled to form a filter unit.

6. The method of claim 1, further comprising forming a plurality of sheets of the first media pack and stacking the plurality of sheets to form a filter unit.

7. The method of claim 6, wherein each sheet comprises a plurality of first media subassemblies.

8. The method of claim 1, wherein the first three-dimensional structure comprises:

a. a plurality of first fins oriented parallel to each other;

b. a plurality of second fins oriented parallel to each other and perpendicular to the first fins, wherein the second fins are stacked on the first fins.

9. The method of claim 8, wherein the first three-dimensional structure further comprises a plurality of pillars formed on the first surface of the second fin.

10. The method of claim 9, wherein at least some of the pillars are formed at an intersection location where the first fin and the second fin intersect.

11. The method of claim 9, wherein:

a. depositing the first fine fiber layer after forming the pillars on the first three-dimensional structure;

b. at least some of the fine fibers of the first fine fiber layer are in contact with a top surface of the column furthest from the second fin; and

c. a gap exists between the first fine fiber layer and the first surface of the second fin.

12. The method of claim 9, wherein the first fine fiber layer is deposited after the pillars are formed on the first three-dimensional structure, and wherein the fine fiber layer is located between the pillars and at least some of the fine fibers in the fine fiber layer are in contact with the first surface of the second fin.

13. A method for manufacturing a filter media, comprising:

a. printing a first three-dimensional structure using an additive manufacturing process, comprising:

i. a plurality of first fins oriented parallel to each other are printed,

printing a plurality of second fins oriented parallel to each other and perpendicular to the first fins, wherein the second fins are stacked on the first fins, and

printing a first plurality of pillars forming a first pillar layer formed on a first surface of the second fin;

14. The method of claim 13, further comprising printing a second three-dimensional structure on the first media component using the additive manufacturing process to form a second media component, wherein the second three-dimensional structure comprises a second plurality of pillars forming a second pillar layer, wherein pillars of the second plurality of pillars are each formed atop one of the pillars of the first plurality of pillars, thereby forming a second media sub-component.

15. The method of claim 14, further comprising depositing a second fine fiber layer on the second media subassembly using the electrospinning process to form a first media assembly after printing the second column layer.

16. The method of any one of claims 1 to 15, wherein the material forming the first three-dimensional structure comprises particles, nanoparticles, fibers, nanofibers, additives, and chemical treatments.

17. The method of any one of claims 1 to 16, wherein the material forming the first three-dimensional structure comprises a chemical treatment that achieves one or more of a change in contact angle, a change in surface roughness, a change in fine fiber adhesion, and a reduction in dust adhesion as compared to a material without the chemical treatment.

18. The method of claim 13, wherein the first three-dimensional structure defines a direct, non-tortuous, open channel from a first side to a second side of the first three-dimensional structure.